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我正在使用 JSF 和我自己的自定义标签/我自己的 taglib，但目前我遇到了一个问题，通过 java 以编程方式添加“复合组件”实例。

我在这里上传了问题：http: //download.dynamicfiles.de/stackoverflow/insertCCprogramatically.zip

package de.dynamicfiles.projects.insertCCprogramatically;

import java.util.Map;
import javax.el.ELContext;
import javax.el.ExpressionFactory;
import javax.el.ValueExpression;
import javax.faces.application.Application;
import javax.faces.application.Resource;
import javax.faces.component.UIComponent;
import javax.faces.component.UIPanel;
import javax.faces.context.FacesContext;
import javax.faces.view.facelets.FaceletContext;

/**
 *
 * @author FibreFoX
 */
public class JSFUtils {

    private static final String JAVAX_FACES_GROUP = "javax.faces.Group";

    /**
     * Source:
     * http://stackoverflow.com/questions/15828540/programmatically-create-and-add-composite-component-in-backing-bean
     *
     * @param parent
     * @param libraryName
     * @param resourceName
     * @param id
     */
    public static void includeCompositeComponent(UIComponent parent, String libraryName, String resourceName, String id, Map<String, String> valueExpressions) {

        System.out.println("includeCompositeComponent > ");
        System.out.println("libraryName > " + libraryName);
        System.out.println("resourceName > " + resourceName);
        System.out.println("parent-id > " + parent.getId());
        System.out.println("id > " + id);

        // Prepare.
        FacesContext context = FacesContext.getCurrentInstance();
        Application application = context.getApplication();
        FaceletContext faceletContext = (FaceletContext) context.getAttributes().get(FaceletContext.FACELET_CONTEXT_KEY);


        // This basically creates <ui:component> based on <composite:interface>.
        Resource resource;
        if (application.getResourceHandler().libraryExists(libraryName)) {
            System.out.println("if the lib exists, load ressource from there");
            resource = application.getResourceHandler().createResource(resourceName, libraryName);
        } else {
            System.out.println("if not, try to load without libname");
            resource = application.getResourceHandler().createResource(resourceName);
        }
        UIComponent composite = application.createComponent(context, resource);
        composite.setId(id); // Mandatory for the case composite is part of UIForm! Otherwise JSF can't find inputs.

        // http://stackoverflow.com/a/16058002/1961102
        if (valueExpressions != null && !valueExpressions.isEmpty()) {
            ExpressionFactory factory = application.getExpressionFactory();
            ELContext ctx = context.getELContext();
            for (Map.Entry<String, String> entry : valueExpressions.entrySet()) {
                ValueExpression expr = factory.createValueExpression(ctx, entry.getValue(), Object.class);
                composite.setValueExpression(entry.getKey(), expr);
            }
        }

        // This basically creates <composite:implementation>.
        UIComponent implementation = application.createComponent(context, UIPanel.COMPONENT_TYPE, JAVAX_FACES_GROUP);

        composite.getFacets().put(UIPanel.COMPOSITE_FACET_NAME, implementation);

        // Now include the composite component file in the given parent.
        parent.getChildren().add(composite);
        parent.pushComponentToEL(context, composite); // This makes #{cc} available.
        try {
            faceletContext.includeFacelet(implementation, resource.getURL());
        } catch (Exception e) {
            e.printStackTrace(System.out);
            //throw new FacesException(e);
        } finally {
            parent.popComponentFromEL(context);
        }
    }
}

当调用“includeCompositeComponent”时，我从 myfaces 得到一个令人沮丧的异常：

java.lang.NullPointerException
        at org.apache.myfaces.view.facelets.impl.FaceletCompositionContextImpl.generateUniqueId(FaceletCompositionContextImpl.java:998)
        at org.apache.myfaces.view.facelets.impl.DefaultFaceletContext.generateUniqueId(DefaultFaceletContext.java:321)
        at org.apache.myfaces.view.facelets.compiler.UIInstructionHandler.apply(UIInstructionHandler.java:87)
        at org.apache.myfaces.view.facelets.tag.composite.ImplementationHandler.apply(ImplementationHandler.java:67)
        at javax.faces.view.facelets.CompositeFaceletHandler.apply(CompositeFaceletHandler.java:49)
        at org.apache.myfaces.view.facelets.tag.composite.CompositeComponentDefinitionTagHandler.apply(CompositeComponentDefinitionTagHandler.java:255)
        at org.apache.myfaces.view.facelets.compiler.NamespaceHandler.apply(NamespaceHandler.java:57)
        at org.apache.myfaces.view.facelets.compiler.EncodingHandler.apply(EncodingHandler.java:48)
        at org.apache.myfaces.view.facelets.impl.DefaultFacelet.include(DefaultFacelet.java:412)
        at org.apache.myfaces.view.facelets.impl.DefaultFacelet.include(DefaultFacelet.java:466)
        at org.apache.myfaces.view.facelets.impl.DefaultFaceletContext.includeFacelet(DefaultFaceletContext.java:393)
        at de.dynamicfiles.projects.insertCCprogramatically.JSFUtils.includeCompositeComponent(JSFUtils.java:76)
        at de.dynamicfiles.projects.insertCCprogramatically.tag.insertCC.encodeChildren(insertCC.java:30)

我错过了什么？！

4

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